In a large bowl, combine the oats, flour, cinnamon, nutmeg, ground cloves, salt, baking powder, and flaxseed (if using). Whisk to combine.
In another bowl, whisk together the maple syrup, applesauce, melted butter, egg, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and mix until just combined.
Fold in the apple chunks.
Scoop the cookie dough onto the prepared baking sheet. Flatten them out to your desired thickness with a spoon or spatula as they will not spread while baking.
Bake for 10-14 minutes. Allow to cool on the cookie sheet for a few minutes before transferring to a wire cooling rack.
Notes
Store in an airtight container at room temperature for 2-3 days or in the refrigerator for 5 days. Any type of apple will work in this recipe.